CVE-2021-26737: Privilege Escalation Using PID Reuse in ZCC macOS

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-10-23 · updated 2026-06-17
Weakness: CWE-346

Description

The Zscaler Client Connector for macOS prior to 3.6 did not sufficiently validate RPC clients. A local adversary without sufficient privileges may be able to shutdown the Zscaler tunnel by exploiting a race condition.

Affected products

Zscaler Client Connector: before 3.6 — fixed in 3.6

How to fix

Upgrade to a fixed version: Zscaler Client Connector 3.6. Check the vendor advisory for mitigations.

References

https://help.zscaler.com/client-connector/client-connector-app-release-summary-2022?applicable_category=macOS&applicable_version=3.6&deployment_date=2022-01-07&id=1388686
https://help.zscaler.com/client-connector/client-connector-app-release-summary-2022?applicable_category=macOS&applicable_version=3.6&deployment_date=2022-01-07&id=1388686

Get alerted when CVE-2021-26737 or the next vulnerability affects your stack